A photonic integrated circuit (PIC) includes monolithically integrated photonic devices or elements and is useful as an optical data link in applications such as optical communications and high performance computing. For mobile computing platforms too, PICs offer a promising I/O for rapidly updating or syncing a mobile device with a host device and/or cloud service. Such optical links utilize an optical I/O interface that includes an optical transmitter and/or an optical receiver including one or more optical waveguide propagating light through one or more passive or active photonic device.
PICs have advantages over optical systems built with discrete optical components due to their compact size, lower cost, and the heightened functionality and/or performance. Many integrated photonic devices however are temperature sensitive and materials that better facilitate monolithic integration often suffer from greater temperature sensitivity. For example, Silicon Photonics (SiPh) technology has clear advantages in terms of manufacturability and scalability, but is faced with the challenge of high temperature sensitivity (e.g., compared to silica, silicon has an index of refraction (RI) that is about 10 times more temperature sensitive).
An optical multiplexer (mux) and de-multiplexer (de-mux) are key components in wavelength division multiplexing (WDM) networks for optical communications and interconnect. To send multiple wavelengths (channels) down a single optical fiber, the wavelengths must be multiplexed (combined) by a mux at one end of the fiber and de-multiplexed (separated) by a de-mux at the receiving fiber end. Optical mux and de-mux elements, such as an Echelle grating or arrayed waveguide (AWG), may integrate well with other optical components like lasers and detectors to form a highly integrated monolithic PIC. However, both of these WDM elements are good examples of temperature sensitive photonic devices.
Many techniques designed to reduce PIC temperature sensitivity, such as active temperature stabilization where a heat source is provided to stabilize the temperature, disadvantageously consume additional electrical power and add system complexity. Therefore, alternatives may be advantageous.